This is framed as being about norms in the media, but in fact it applies to public life, and public debates, more broadly.  Everyone has things that are taken for granted; everyone has things that are plausibly contested, and everyone has things that they think are simply abhorrent, and the boundaries separating these three classes vary all the time:

In 1986, the media historian Daniel Hallin argued that journalists treat ideas as belonging to three spheres, each of which is governed by different rules of coverage. There’s the “sphere of consensus,” in which agreement is assumed. There’s the “sphere of deviance,” in which a view is considered universally repugnant, and it need not be entertained. And then, in the middle, is the “sphere of legitimate controversy,” wherein journalists are expected to cover all sides, and op-ed pages to represent all points of view.

Also this: “One of the central instabilities of the era is that media and cultural power runs 10 years ahead of demography, and political power 10 years behind. ”